Detaljerad miljöinformation

Environmental Risk Classification

Predicted Environmental Concentration (PEC)

PEC is calculated according to the following formula:

PEC (μg/L) = (A*10⁹*(100-R))/(365*P*V*D*100) = 1.5*10^-6*A(100-R)

PEC = 0,0014 μg/L

Where:

A = 9,178 kg (total sold amount API in Sweden year 2019, data from IQVIA).
R = 0 % removal rate (due to loss by adsorption to sludge particles, by volatilization, hydrolysis or biodegradation) = 0 if no data is available.

P = number of inhabitants in Sweden = 9 *10⁶ 

V (L/day) = volume of wastewater per capita and day = 200 (ECHA default (1))

D = factor for dilution of waste water by surface water flow = 10 (ECHA default (1))

Predicted No Effect Concentration (PNEC)

Ecotoxicological studies

Algae (Desmodesmus subspicatus):

EC50 /72 h (growth inhibition, growth rate) = 25.3 µg/L
NOEC/72 h = 5.6 µg/L (guideline OECD 201) (2)

Crustacean (waterflea Daphnia magna):

Chronic toxicity

NOEC /21 days (reproduction) = ≥ 729 μg/L (guideline OECD 211) (3)

Fish:

Chronic toxicity (fathead minnow Pimephales promelas)

NOEC 21 days (fish reproduction test; fecundity, sexual reversal) = 0.0001 μg/L (EC₁₀) (OECD 229) (4) 

NOEC 126 days (fish partial life-cycle test, endpoints: mortality, growth, sexual development, fecundity) = 0,00047 µg/L, LOEC 0,00164 µg/L (fertilization rate, sex ratio) (5)

PNEC = 0.00001 μg/L (Lowest chronic NOEC fish = 0,0001 µg/L; AF 10)

Environmental risk classification (PEC/PNEC ratio)

PEC/PNEC ratio: 0.0014/0.00001 = 141, i.e. PEC/PNEC >10 which justifies the phrase Use of levonorgestrel has been considered to result in high environmental risk.

Degradation

Biotic degradation

Ready degradability: not readily biodegradable

Levonorgestrel was studied for aerobic biodegradability in water in a manometric respiration test according to guideline OECD 301F (6). Levonorgestrel was introduced into the test system at a concentration of 200 mg/L as theoretically oxidizable carbon. It was not degraded after 28 days. Hence, it is not readily biodegradable.

A study on transformation in aquatic/sediment systems according to test guideline OECD 308 was conducted (7). The transformation of [¹⁴C] levonorgestrel in sediments and natural water was assessed in two different aerobic sediment/water systems. Levonorgestrel was incubated in glass vessels containing sediment and overlaying water over 100 days. The results of the study indicate that levonorgestrel is distributed to the sediment compartment, however, relevant amounts remained in the water phase (22 and 43% for the fine and coarse sediment, respectively). The degradation rate was 6-7% at the end of the incubation period. The DT₅₀ (disappearance half-life from the water phase) for parent compound in water was estimated with 2.5 and 3.2 days for the fine and coarse sediment, respectively.

The overall disappearance half-life from the system exceeded the threshold of 120d described in the FASS guidance. Therefore, levonorgestrel can be classified as being potentially persistent.

Abiotic degradation

Hydrolysis:

Levonorgestrel is hydrolytically stable (pH 7, 25ºC) (FDA TAD 3.09) (8)

Bioaccumulation

Partitioning coefficient:

Log P_OW 3.55 (Shake flask method, FDA TAD 3.02) (9)

A bioaccumulation study of the bioaccumulation potential in fish was conducted according to OECD 305. (10)

Fish (bluegill sunfish Lepomis macrochirus) were exposed in two treatment groups to ¹⁴C-labeled levonorgestrel for 28 days followed by a depuration phase of 14 days (11). The mean measured concentration of levonorgestrel (based on ¹⁴C analysis) was 6.1 and 42.1 ng/L for the low and high concentration, respectively, during the exposure phase. The BCF_ss (bioconcentration factor at steady state) was 250 and 119 for group 2 and 3, respectively, calculated based on the mean measured water concentration and the steady-state fish tissue concentration. Based on lipid normalized (6%) values, the BCF_ss was 227 and 108 for group 2 and 3, respectively. The concentration of ¹⁴C in fish tissue decreased rapidly during the exposure phase most likely due to increased metabolization and subsequent rapid excretion.

Justification of chosen bioaccumulation phrase:

According to the BCF of 119 to 250, levonorgestrel has low potential for bioaccumulation. 

Excretion (metabolism)

Systemically available levonorgestrel is mainly excreted in the hydroxylated and to a lesser extent, in a conjugated form. Only a small fraction is released unchanged (11).

PBT/vPvB assessment

Levonorgestrel is not PBT/vPvB, because the threshold of a BCF of 2000 was not exceeded.

References

(1) ECHA, European Chemicals Agency. 2008 Guidance on information requirements and chemical safety assessment.

http://guidance.echa.europa.eu/docs/guidance_document/information_requirements_en.htm

(2) Growth inhibition test of levonorgestrel (BAY 86-5028) on the green algae Desmodesmus subspicatus. Nonclinical Drug Safety, Bayer Pharma AG, study no. TOXT2082435, report no. A52865 (2011)

(3) Reproduction study of levonorgestrel (ZK18206) in Daphnia magna. Nonclinical Drug Safety, Bayer Pharma AG, study no. TOXT6081124, report no. A49686 (2011)

(4) Short-term reproduction tests with levonorgestrel (ZK 18206) on the fathead minnow (Pimephales promelas). Nonclinical Drug Safety, Bayer Schering Pharma AG,study no TOXT4078685, report no. A39905 (2011)

(5) Zebrafish (Danio rerio) Partial life stage test, Flow through conditions. Drug Discovery, Bayer AG, study no. T103549-2, report no. R-12907 (2019)

(6) Study on the biodegradability of Levonorgestrel (ZK 18206) in the manometric respiration test. Nonclinical Drug Safety, Bayer Schering Pharma AG, study no. TOXT2082138, report no. A51399 (2011)

(7) Levonorgestrel (BAY 86-5028): Aerobic Transformation in Aquatic Sediment Systems. Nonclinical Drug Safety, Bayer Healthcare AG, study no.T5081646EXT, report no. A56339 (2011)

(8) Levonorgestrel, ZK18206, Report on physicochemical properties, Rate of hydrolysis. General Physical Chemistry, Schering AG, study no. APC 94/158, report no. LD06EY10 (1999)

(9) The octanol/water partition coefficient of levonorgestrel (ZK18206). General Physical Chemistry, Schering AG, study no. APC 93/103a, report no. LD16 (1998)

(10) Bioconcentration flow-through fish test with levonorgestrel [BAY 86-5028 (14-C)], Nonclinical Drug Safety, Bayer HealthCare AG, study no. TOXT9082441, report no. A53418 (2011)

(11) Stancyk, F., Roy, S.: Metabolism of levonorgestrel, norethindrone, and structurally related contraceptive steroids. Contraception 42, 67-96 (1990)